1. Field of the Invention
The present invention relates generally to an electrical connecting device and, more particularly, to a connector used for electrically connecting two circuit boards with each other. The present invention further relates to an electrical contact element used in such a connector.
2. Description of the Related Art
Various types of connectors used for electrically connecting two circuit boards with each other are well known in the art. In such connectors, it is important that electrical contact elements, used therein as conductors for establishing the electrical connection between two circuit boards, are fixedly supported at appropriate positions in an electro-insulating body of the connector, to ensure and maintain the stable connection of the circuit boards.
FIGS. 1A to 1C show an example of a conventional electrical contact element used in such connectors. The electrical contact element 1 as illustrated includes two opposed contact ends, one 1a of which is fixedly bonded to a terminal on a first circuit board and the other 1b is slidingly engaged with a terminal on a second circuit board, and an intermediate section 1c integrally joining the first and second contact ends 1a, 1b with each other. The intermediate section 1c is provided integrally with a projection 2 which is tightly press-fitted into a corresponding slit 4 formed in the electro-insulating body 5 of the connector. To ensure that the contact element is fixedly supported in the electro-insulating body 5, a plurality of small bumps 3 are generally formed on a peripheral edge of the projection 2.
When the electrical contact element 1 is formed by stamping a sheet metal material, it is difficult to precisely stamp the small bumps 3 into mutually identical dimensions. If the small bumps 3 have mutually different dimensions, as shown in FIGS. 1B and 1C, the electrical contact element 1 is supported in an angularly displaced position about the projection 2 in the electro-insulating body 5, and the first contact end 1a of the contact element 1 is shifted from an appropriate position in a deviation .delta.. As a result, the first contact ends 1a of the plural contact elements 1 disposed in an array in the electro-insulating body 5 are unevenly positioned, which makes it difficult to ensure an accurate electrical connection between the circuit boards. Therefore, the conventional connector using the above contact element 1 has problems in that the positional unevenness of the first contact ends 1a of the plural contact elements 1 should be corrected before the connector is mounted on the circuit board, and that the productivity of the electrical connecting system including the connector is thereby deteriorated.
Also, in the field of circuit board connectors, a connector used for a circuit board on both sides of which electronic devices are mounted and terminals are formed, such as a DIMM (Dual Inline Memory Module) substrate or a SIMM (Single Inline Memory Module) substrate, is known. FIGS. 2A and 2B partly show an example of such a conventional connector.
The connector as illustrated includes an electro-insulating body 6 which is provided with a base 7 for supporting electrical contact elements in a mutually isolated manner, and a pair of columns 8 extending in the same direction from longitudinally opposed ends of the base 7. Each column 8 includes an inner resilient part 8a and an outer support part 8b. The inner resilient part 8a of the column 8 is elastically deformable and displaceable in a direction away from the opposed resilient part 8a, to permit a circuit board not only to be snap-fitted between the columns 8 and slidingly engaged with the contact elements, but also to be disengaged from the connector. A bracket 9 is attached to the outer support part 8b, to restrain the displacement of the resilient part 8a away from the opposed resilient part 8a, i.e., an outward displacement, to a certain degree.
In this type of connector, the inner resilient part 8a is prevented from being broken, or deformed in excess of the elastic limit of the material due to an external force applied thereto in an outward direction (shown by an arrow G.sub.1), by a projection 9a of the bracket 9 attached to the outer support part 8b, which extends toward the inner resilient part 8a. However, since the projection 9a of the bracket 9 can merely stop the outward displacement of the inner resilient part 8a, if the external force is inadvertently applied to the inner resilient part 8a in an inward direction (shown by an arrow G.sub.2) to displace it toward the opposed resilient part 8a when the circuit board is not inserted between the columns 8, the problem arises that the inner resilient part 8a may be broken or deformed in excess of the elastic limit of the material.